Refine shell status icons and window controls; add installer

shell/ferese-shell/assets/icons/status/battery-empty.svg

@@ -1,4 +1,4 @@
-<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round">
-  <rect x="2" y="6" width="18" height="12" rx="2.8"/>
-  <path d="M22 10v4"/>
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 24" role="img" aria-label="Battery empty">
+<rect x="2" y="6" width="25" height="12" rx="3" fill="none" stroke="currentColor" stroke-width="1.5"/>
+<rect x="28" y="10" width="2" height="4" rx="1" fill="currentColor"/>
 </svg>